The invention relates to data storage and in particular to data block storage services that store data blocks across a plurality of servers.
The client/server architecture has been one of the more successful innovations in information technology. The client/server architecture allows a plurality of clients to access services and resources maintained and/or controlled by a server. The server listens for, and responds to, requests from the clients and in response to the request determines whether or not the request can be satisfied. The server responds to the client as appropriate. A typical example of a client/server system is where a server is set up to store data files and a number of different clients can communicate with the server for the purpose of requesting the server to grant access to different ones of the data files maintained by the file server. If a data file is available and a client is authorized to access that data file, the server can deliver the requested data file to the server and thereby satisfy the client's request.
Although the clientserver architecture has worked remarkably well it does have some drawbacks. In particular, the clientserver environment is somewhat dynamic. For example, the number of clients contacting a server and the number of requests being made by individual clients can vary significantly over time. As such, a server responding to client requests may find itself inundated with a volume of requests that is impossible or nearly impossible to satisfy. To address this problem, network administrators often make sure that the server includes sufficient data processing resources to respond to anticipated peak levels of client requests. Thus, for example, the network administrator may make sure that the server comprises a sufficient number of central processing units (CPUs) with sufficient memory and storage space to handle the volume of client traffic that may arrive.
Even with a studied provisioning of resources, variations in client load can still burden a server system. For example, even if sufficient hardware resources are provided in the server system, it may be the case that client requests focus on a particular resource maintained by the server and supported by only a portion of the available resources. Thus, continuing with our above example, it is not uncommon that client requests overwhelmingly focus on a small portion of the data files maintained by the file server. Accordingly, even though the file server may have sufficient hardware resources to respond to a certain volume of client requests, if these requests are focused on a particular resource, such as a particular data file, most of the file server resources will remain idle while those resources that support the data file being targeted by the plurality of clients are over burdened.
To address this problem, network engineers have developed load balancing systems that act as a gateway to client requests and distribute client requests across the available resources for the purpose of distributing client load. To this end, the gateway system may distribute client requests in a round-robin fashion that evenly distributes requests across the available server resources. In other practices, the network administrator sets up a replication system that can identify when a particular resource is the subject of a flurry of client requests and duplicates the targeted resource so that more of the server resources are employed in supporting client requests for that resource.
Although the above techniques may work well with certain server architectures, they each require that a central transaction point be disposed between the clients and the server. As such, this central transaction point may act as a bottle neck that slows the servers response to client requests. Accordingly, there is a need in the art for a method for distributing client load across a server system while at the same time providing suitable response times for these incoming client requests.